The present invention is directed toward a system for locating a junction box behind a wall and more particularly, toward a system that uses magnets to locate the box.
In building construction, drywall is typically installed on wall studs over junction or electrical boxes. In order to locate the box, measurements relative to the walls, floor or ceiling are taken and are then used to determine where the hole should be cut in order to reach the box. This is a rather inaccurate and time consuming way to locate the box.
Several different methods for locating electrical or outlet boxes have been proposed. One method is by using magnets or ferromagnetic material. For example, U.S. Pat. No. 6,708,421 to Crorey discloses a device for locating a junction box behind a wall. The device includes a first magnet positioned within the box and a second magnet positioned on the outer surface of the wall in order to locate the magnet or magnets located within the box. However, when installing sheet material on walls, the sheet material is never precisely parallel with the junction box face until the hole for the box is cut. This causes a separation between the magnet in the box and the inner surface of the sheet material which can be a quarter inch or more. As magnetic attraction decreases exponentially with distance, this small space can result in unsatisfactory attraction on the external magnet.
Also, U.S. Pat. No. 6,452,097 to DeWall discloses a system for locating an outlet box behind drywall. A magnet may be positioned within the box via a plate, a wire, or magnet mounting tape. A magnet sensing device is used on the outer surface of the wall in order to locate the box. However, it appears that the magnet must be centrally located within the box in order for the sensing device to locate the magnet. In addition, the same separation between the magnet in the box and the sheet material which appears in Crorey exists in DeWall. Even further, the magnetic tape or magnets on a wire cannot protect the contents of the junction box from damage in the cutting process. Additionally, if the magnet is mounted flush with a plate in the box, it can be difficult to remove as there is no protrusion to grasp after cutting the hole.
Therefore a need exists for a method for locating a junction box in a simple, accurate, and efficient manner.